This invention relates to an apparatus to be driven reciprocally for transporting filter plates in filter presses, the apparatus including a pair of reciprocally movable carriers each provided with a drive dog and a stop dog one of which is alternatively raisable and tiltable in operative relation to each other, such that the filter plates held pressed against a stationary end plate are transported one by one toward a movable end plate in its retracted position by the cooperation of the dogs with the handles of the filter plates movably supported on side bars.
Various apparatus of the type described have been proposed which include such carriers. To transport the filter plates in the same direction repeatedly on completion of every filtration cycle, the carriers must always be returned to a standby position after the transport of the filter plates. U.S. Pat. No. 3,306,455 discloses an apparatus including a carrier which is returnable in a simple fashion along a straight path for the transport of the filter plates. The carrier, having a drive dog and a stop dog, is attached to a drive belt and provided with a cam which is movable relative to the carrier. When the cam comes into contact with a stopper at each end of the filter press, the resulting relative movement between the carrier and the cam brings the drive dog and stop dog into a returnable or standby position. The operation of the dogs in turn actuates a switch to return the carrier or to halt the same in a standby position. Thus the apparatus requires the combination of the two components, namely the carrier and the cam, which are rendered movable relative to each other. Accordingly the apparatus is complex in construction and difficult to make because the carrier and the cam must be maintained in accurate position relative to each other and the parts must be dimensioned and assembled properly. Additionally the adhesion of the cake tends to disturb the position relationship between the two components at the onset of as well as during the operation, thus reducing the stability of the operation including the transport of the filter plates.
U.S. Pat. No. 3,598,240 discloses another apparatus comprising a carrier which is adapted to travel reciprocally to transport the filter plates forward and also backward so that the transport means presses, the filter plates together for filtration and also separates the plates from one another for the removal of the cake after filtration. Because of such a structure, the apparatus does not include means for returning the carrier to its original position after the transport of the filter plates. Each of drive and stop dogs is supported at a movable point and has a front end supported by a loose link and a spring-loaded tail end adapted to be guided by a cam face. The apparatus is therefore very complex in construction, and the dogs operate in delicate fashion in accordance with the shift of the support point, hence reduced stability. Thus the disclosed apparatus is susceptible to malfunction or failure for example due to the deposition of the cake.
The function given to the filter plate transporting apparatus of this type varies from apparatus to apparatus depending on the mode of the operation. Thus various transport apparatuses have heretofore been provided, each as adapted for the particular function required. However the known apparatuses are complex in construction and are not satisfactory in respect of the stability of operation. Moreover no apparatuses have been provided which are provided with several different functions.